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118 Final

Unit 1, 2, 6

WTF is this?No shit Sherlock
When were x-rays discovered? By whom? 1895, Wilhelm Conrad Roentgen
(+/-) Charge of __ keeps electron cloud together? Negative (-) charge of Focusing Cup
__ is electric motor made of electromagnet pairs? __ turns the Target? Stator, Rotor
3 Functions of Glass Envelope? 1 Create Vacuum, 2 Insulation from shock, 3 Dissipates heat to insulating oil
Leakage radiation regulated limit? 100 mR/hr at 1 meter
What unit measures Tube Current? mA
__ is when x-rays are produced they fly off in spherical patterns? Isotropic Emission
What is the source of ELECTRONS in the tube? What is the source of X-RAYS? Filament (electrons), Target (x-rays)
Large Focal Spot provides more DETAIL, and uses MORE Energy than small focal spot (T/F)? False - Large more energy, LESS detail
During Ionization, what is left after an electron is knocked out of orbit? Ion Pair remains (+ Atom, - Free Electron)
2 x-ray producing Interactions of electrons at Target? Bremsstrahlung & Characteristic
Interaction that results from lost kinetic energy? Is this Ionizing or Nonionizing? Brems - Nonionizing
Interactions responsible for High Energy Photons? (Most x-rays are __) Bremsstrahlung
X-ray photons created by inner shell electrons being ejected? Are they Ionizing or Nonionizing? Characteristic - Ionizing
__ is when an electron is ejected from orbit/shell? Ionization
What kVp required for Characteristic Interactions at Target? 69.5+
Interaction responsible for low energy x-rays? Characteristic
How does kVp affect QUALITY of x-rays? How does kVp affect QUANTITY? ↑ kVp = ↑ Penetrability, only Influences Quantity
What does mA measure? How does it affect QUANTITY of x-rays? mA = Tube Current, ↑ mA = ↑ electrons/Quantity
Total Tube Filtration must be __ ? +2.5 mm Al @ 70 kVp
Tube Filtration lowers OCCUPATIONAL dose (T/F)? False - ↓ Patient dose
Line Focus Principle states Effective focal spot LARGER than Actual focal spot (T/F)? False - Effective Smaller
Heat Unit Formula HU = mA x time x kVp x generator factor
3 Phase generator factor? High Frequency GF? 1.35, HF 1.4
Varying parts absorb x-rays differently, allowing __ to create structurally representative images. Differential Absorption
High atomic # has more absorbing power creating MORE radiographic density (T/F)? False - More absorbent = Less Density
More Differential Absorption = (High/Low) Density = (High/Low) Brightness? Low Density, High Brightness
Structures that appear with Low Density or High Brightness have (More/Less) Absorption? More Absorption
As x-ray photons pass through matter, what 3 processes Attenuate the beam? Transmission, Photo Electric Absorption, Compton Scatter
4 factors affecting Beam Attenuation? Tissue thickness, Type of tissue, Tissue Density, Beam quality
Tissue Thickness affects Beam Attenuation at what rate? -50% for each 4-5 cm
__ interactions, which are Nonionizing with no energy transfer, occur with x-ray photons below 10 KeV? Coherent Scatter (photon w matter)
__ interactions of photons that convert incident matter into a Positron & a Negatron? Occur at what energy level? Pair Production, +1 MeV
In regards to radiographic quality, what impacts Visibility? Contrast & Density/Brightness
In regards to radiographic quality, what impacts Sharpness? Recorded Detail & Distortion
High kVp increases __ & __ ? High kVp decreases __ & __? ↑ Transmission & Scatter = ↓ Absorption & Contrast
kVp controlling factor for both Digital and Film CONTRAST (T/F)? True
__ is IR's ability to differentiate btwn objects with similar subject contrast? Contrast Resolution (system can see diffs)
__ refers to the smallest object a digital system can detect? Spatial Resolution
Size Distortion (or __ ) is affected by __ & __ ? Magnification - SID & OID
Type of Shape Distortion when part is misaligned? Foreshortening
Type of Shape Distortion when Tube or IR are misaligned? Elongation
__ has greatest effect on Size Distortion? OID
↑ OID = __ Magnification ↑ OID = ↑ Mag
↑ SID = __ Magnification ↑ SID = ↓ Mag
Type of Image Artifact that is more BLACK? Plus Density Artifact
Type of Image Artifact that is more BRIGHT? Minus Density Artifact
__ refers to the crispness of lines on a radiograph? Recorded Detail
Higher Spatial Resolution with SMALLER Pixels & LARGER Matrix size (T/F)? True (↑ Matrix = ↓ Pixel = ↑ Resolution)
__ determines the number of shades of gray a pixel can display? Bit Depth
__ is the distance btwn 2 adjacent pixels' center points? Pixel Pitch
4 factors affecting Exposure Index (EI) mAs, kVp, total area irradiated, object exposed
What stores the latent image on film? Latent imaging centers of Film Emulsion
General range for Optical Densities? Diagnostic range for Optical Densities? Gen 0-4, Diagnostic .5-2
__ is the unique graphic display of the distribution of pixel values extracted from the IR for an image? Histogram
__ is the PSP Reader's ability to read & differentiate exposed & unexposed areas of a plate (Collimation lines)? Exposure Field Recognition
The PSP reader will overcompensate for Poor Collimation & Alignment by __ , which reduces __ ? Reading the whole plate reduces Image Quality
When Exposure Field Recognition within the PSP Reader works properly, __ are recognized and image data field is well defined? Field Margins
For DR panels, the exposure field edge is recognized as __ ? Well-defined boundary (End of DEL values)
The X axis of a Histogram represents __ ? The Y axis represents? X - Receptor Exposure, Y - # of pixels at each value
2 formats of reference Histograms? A Priori & Neural
(A Priori/Neural) Histograms compare 2+ predefined ranges & selects closest match? (A Priori/Neural) Histograms compare the range of values btwn the greatest & least attenuators? Neural (2+), A Priori
This type of A Priori Histogram uses BONE as the greatest attenuator and the SKIN MARGIN (Outer surface of pt) as least attenuator? Type 1 - Bone & Skin Margin
This type of A Priori Histogram uses BONE as the greatest attenuator and has no skin margin so uses ex. Intestinal Gas as least attenuator? Type 2 - No Skin Margin, Bone highest
This type of A Priori Histogram reproduces an image SANS SIGNIFICANT attenuator? Type 3 - Ignores Sig. Atten. like Barium/prosthetics
This type of histogram analysis compares predefined data to recently exposed data, comparing multiple to find a match? Neural Histogram
The process of matching the captured image PIXEL values to standardized values is __ ? Automatic Rescaling
__ refers to gradual increases in patient dose through technique compensation (undetectable on radiograph)? Dose Creep
This final step in Histogram Analysis sets the gray scale, or contrast range, by changing linear representation to a curve & by changing the pixel values to ideal level? Look-up Table (LUT)
Histograms and Look-up Tables are uniquely specific to anatomy (T/F)? True
Requirements for MONITORS for Soft Copy Viewing of digital images? Minimum 256 shades of gray (8 bit) & 2.5 lp/mm
__ sets the midpoint for the Range of Brightness displayed on a monitor? (↑ __ = ↑ Brightness) Window Level
__ controls the DISPLAY of contrast? Window Width
(Wide/Narrow) Window Width displays many grays, lower contrast? (Wide/Narrow) Window Width displays few grays? Wide - Long Scale, Narrow - Short Scale
Post processing...
__ is the computer system that manages images? __ is the system for patient medical records? PACS, RIS/HIS (pt med info)
__ regulates PACS communications with other modalities? DICOM - Dig Imaging and Communication in Medicine
__ regulates communication standards for patient medical information? HL7 - Health Level Seven Standard
Created by: RadTechTKD